1. Field of the Invention
The present invention relates to compositions and methods for the control of hoof diseases. In particular, solutions effective in treating or preventing papillomatous digital dermatitis, interdigital phlegmon, interdigital dermatitis, laminitis, white line disease, heel erosion and other hoof diseases are disclosed.
2. Description of the Related Art
Infectious diseases of the hooves, such as hairy hoof warts (papillomatous digital dermatitis, or “PDD”), hoof rot (interdigital phlegmon), stable hoof rot (interdigital dermatitis), laminitis, white line disease and heel erosion are common in farm animals such as sheep, goats, horses, dairy cows and beef cattle. These diseases are a significant source of lameness, and produce a large economic and humane impact on the farming industry.
PDD is an infection of the epidermis of an animal's digit that is believed to be caused by Treponema organisms, which survive under the skin in conditions of low oxygen, temperatures between 30° C. and 37° C., and a pH range of 7.2 to 7.4. PDD infections range from painful, moist lesions to raised, hairy, wart-like lesions that can result in severe lameness, and even death, if not properly treated. With respect to dairy cows, hoof warts are also associated with losses in milk production, reproductive efficiency and body weight. Hoof rot, or interdigital phlegmon, is an infection of the soft tissue between the claws of the feet, where bacteria invade the skin of the foot at injured or damaged skin areas. Initially, the infection causes a painful swelling of the skin between the claws. A fissure or crack then develops along the swollen area for part or all of the length of the interdigital space. If left untreated, hoof rot can enter the joints, bones, and/or tendons of the foot, making recovery from the infection unlikely. Animals with hoof rot can have a mild fever, loss of appetite and accompanying weight loss, and develop mild to severe lameness. Interdigital dermatitis, or stable hoof rot, is generally a chronic inflammation of the skin in the interdigital cleft. The condition may cause lameness or heel crack/heel erosion. These three hoof diseases—papillomatous digital dermatitis, interdigital phlegmon and interdigital dermatitis—are caused by bacterial infections, and they may be accompanied by or lead to complications with other hoof diseases such as laminitis, white line disease and heel erosion.
Treatment or prevention of hoof diseases generally involves topical application of antibiotics to affected areas. However, antibiotics are expensive, and, particularly when treating cattle, concerns related to the presence of antibiotics in beef and milk arise. Further, it is well known that extended use of antibiotics leads to antibiotic-resistance, and the development of more aggressive strains of bacteria.
The use of chemical germicides to treat or prevent hoof diseases is also common. For example, germicidal compositions containing copper sulfate, zinc sulfate, sulfamethazine, quaternary ammonium compounds, hydrogen peroxide and/or peracetic acid are known.
Application of the antibiotic or germicidal compositions is typically carried out by making the animals walk through a footbath. However, after a few animals have passed through the footbath, the solution becomes contaminated with manure. Many formulas that are currently used for footbath solutions loose their activity in the presence of manure. As a result, these baths can become a breeding ground for bacteria, and can accelerate the spread of infectious hoof diseases, rather than prevent them. Infectious hoof diseases can also be treated by a topical spray, footwrap or application of a foam or gel. However, the hoof is likely to be highly contaminated with manure, dirt or other soils before and/or shortly after application.
Other germicides, such as iodine or chlorine, are extremely effective disinfectants for other purposes, but they are not useful for a footbath solution because they quickly react with manure, which reduces the efficacy of the active ingredients. Germicides such as salicylic acid are also ineffective for footbath solutions due to limited solubility.